1. Field of the Invention
The present invention relates to a hard disk drive. More particularly, the present invention relates to the swing arm and head gimbal of a head stack assembly (HSA) of a hard disk drive.
2. Description of the Related Art
The hard disk drive (HDD) of a computer or the like retrieves and records data from and onto a data storage disk using a read/write head. To this end, the read/write head is moved to a desired position over a recording surface of the disk while being maintained at a predetermined height above the recording surface of the disk. More specifically, the read/write head is located at the leading end of a head gimbal. The head gimbal also includes an elastically deformable suspension which supports the read/write head, and a flexure supported by a swing arm. The head gimbal, the swing arm to which the head gimbal is mounted, a pivot bearing supporting the swing arm so as to be rotatable in the HDD, and an actuator for generating an electromagnetic force that will rotate the swing arm about an axis of the pivot bearing make up what is referred to as a head stack assembly (HSA) of the HDD.
The HDD also includes a housing forming the exterior of the HDD, and a spindle motor to which the data storage disk is mounted. The HSA and spindle motor are mounted to the frame. The spindle motor rotates the disk at a high speed during a read/write operation in which the read/write head is recording to data onto or reading data from a disk. At this time, the head is lifted above the surface of the disk, against the biasing force exerted thereon by the suspension, by the force of an air stream generated between the head and the rotating disk.
However, in the HDD described above, the head gimbal of the HSA protrudes outwardly from the swing arm. As a result, the windage generated between the swing arm and the disk creates a vortex around the head gimbal. This irregular air flow, defective spindle motor parts, and eccentricity between the spindle motor and the disk cause the head gimbal to flutter. Fluttering adversely affects the performance of the read/write head.
Specifically, the fluttering of the head gimbal results in track mis-registration (TMR) and the generation of a position error signal (PES). Track mis-registration (TMR) is a situation in which the read/write head is not aligned with the desired track of the disk onto/from which data is being recorded/read. The position error signal (PES) is a signal generated when TMR occurs and represents the magnitude of the TMR. Fluttering, therefore, is especially problematic in an HDD whose data storage disk has a large number of tracks per inch (TPI), i.e., whose data storage disk has a high track density. In particular, fluttering makes it difficult to execute the servo control of the HSA with the precision required for the read/write head to follow the desired track during a read/write operation.